1. Field of the Invention
The invention relates to a running apparatus within a pipe which is applied to a maintenance inspection and a repair operation within a pipe in an underground piping for a city gas and a pipe construction for various kinds of plants, and more particularly to a running apparatus within a pipe suitable for running within a curved pipe.
2. Description of the Related Art
For example, in a supply system for a city gas, most of gas pipes called as a main pipe is a pipe having a diameter 10 mm to 200 mm, and an extending distance thereof is ten thousands km or more, so that a mechanism of moving a sensor within the pipes is unavoidable for maintaining and inspecting the pipes. Further, the gas pipes are frequently provided under a main road, and it is necessary to reduce a number of excavating the pipes in view of influence to a traffic and a cost reduction, so that it is desired to develop a running apparatus which can move the sensor within the pipes as long as possible.
The running apparatus of this type includes a push type, a pressurizing type and a self-propelled type, and the self-propelled type particularly has an excellent performance in comparison with the push type and the pressurizing type since it has its own drive force. This self-propelled apparatus includes a crawler type, a wheel type, a peristalsis type and a walk type, and the wheel type is advantageous in view of making a size compact and a fast moving speed.
However, in this wheel type running apparatus, there is a problem that a sufficient control can not performed at a time of passing through a curved pipe so called an elbow, so that a center axis of the running apparatus does not coincide with a pipe axis of the curved pipe. Particularly, in a pipe having a different diameter called a miter bend, since a shape of the pipe is suddenly changed, there is a risk that an attitude of the running apparatus is crumbled and the running apparatus can not run.
Further, in the wheel type running apparatus having no steering mechanism, there is a risk that the running apparatus can not avoid an obstacle within the pipe and can not run in some cases. In this case, when mounting a steering mechanism to the wheel type running apparatus, an increase of a weight of the running apparatus and a complication of a shape of the apparatus are caused, so that not only a motion performance is reduced but also a reduction of an economical efficiency is caused.
Still further, in spite that understanding the shape of the pipe passage is indispensable information for maintaining the pipe, in the case of an old pipe, the drawings at a time of building are not sufficiently prepared and a history of changing the pipe is not clear, so that there are many cases that the shape of the pipe passage to which the running apparatus is applied can not be accurately understood.